EELATIOX TO MESOZOIC ROCKS IX THE LHI'ONTIXE ALPS. 



21' 



The Alp Vitgira affords the following evidence. Its southern 

 slopes overlook a glen called the Val Rondadura : the floor of this is 

 the gneiss of the district, over which, according to the map, 

 rauchwacke occurs some distance up the glen ; but there is no trace 

 of this rock at the south-eastern angle of the Alp Yitgira. Here, 

 at the base of the slope, we have Black-garnet or Dark-mica schist 

 interbanded with quartzose rock (fig. 8). Except that these dark 



Pig. 8. — Diagrammatic Section, Alp Vitgira. 



A. Gneiss. A^. Gneiss with cleavage-foliation. 



B. Black-garnet schist, banded with quartzite. 



0. Jurassic rock. ^ Breccia. D. Covered ground. 



schists are more squeezed and slaty in aspect than is usual near the 

 Lago di Ritom, this group is very like the banded Black-garnet schist 

 of the Val Piora ; and microscopic examination fully confirms the 

 impression, gained in the field, as to the identity of the two groups 

 of rock. These banded schists form a craggy buttress, and the part 

 exposed may be some 200 feet in thickness. Crossing this in a 

 northerly direction, we find that everything for a short interval is 

 concealed by turf. Then come outcrops of interbanded calcareous 

 and slaty (rather fissile) rocks. These contain here and there (but, 

 so far as we saw, less abundantly than on Scopi) the usual mineral 

 spots and prisms. The more fissile layers exhibit sheen surfaces, 

 but the matrix in which these minerals are imbedded looks, even to 

 the unaided eye, very different from that of one of the true schists. 

 Here also we found ill-preserved Belemnites, with indications of 

 other organisms. One outcrop consisted of a dark grey sandy 

 mudstone interbanded with layers, which suggested the presence of 

 detritus from gneiss ; below this was a phyllite, which might have 

 obtained its materials from the Dark-mica schist ; these contained 

 Belemnites, &c. Shortly beyond this the usual gneiss crops out and 

 continues away to the north. 



(c) Tlie Nufenen Pass. 



The sections here are less accessible than those on the Lukmanier, 

 but accommodation — though very rough — for the night can be found 

 at AH'acqua (5260 feet), on the eastern side of the pass, about 

 2| hours below the summit (8006 feet). Between All'acqua and 



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